Getting started with rpic

In rpic: The 'pic' Graphics Language Rendered to SVG, PNG and PDF

knitr::opts_chunk$set(collapse = TRUE, comment = "#>", eval = FALSE)

rpic renders diagrams written in Brian Kernighan's pic picture-drawing language: you describe a drawing by walking around a plane dropping primitives — boxes, circles, lines, arrows — with relative positioning doing the layout for you. The engine is pure Rust (no troff, no LaTeX, no system dependencies) and outputs SVG, PNG and PDF.

All diagrams in this vignette were pre-rendered with rpic_svg() — the code chunks show exactly the source that produced each figure. The full language reference, extension pages and a live playground are at rpic.dev.

A first picture

Primitives placed in sequence flow in the current direction (right, by default); arrow connects them; arc bends between named positions:

library(rpic)

svg <- rpic_svg('
boxht = 0.35; boxwid = 0.8
A: box "input"
arrow
box "process" fill 0.9
arrow
E: ellipse "output"
arc cw -> from A.n to E.n
')

Positioning

Objects can be labelled (A:), addressed by compass corners (.n, .e, .c, …) or by ordinals (last circle, 2nd box), and placed with expressions — including fractions of the way between two points:

rpic_svg('
A: box "A" wid 0.6 ht 0.4
B: box "B" wid 0.6 ht 0.4 at A + (1.6, 0)
line dashed from A.e to B.w
circle rad 0.06 fill 0 at 1/2 between A.e and B.w
"midpoint" at last circle.s below
arrow from A.n up 0.3 then right 1.6 then down 0.3 to B.n
"the long way" at 1/2 between A.n and B.n + (0, 0.42)
')

Programmability

pic is a little language: for/if, variables, define macros with $1…$9, and sprintf are all built in:

rpic_svg('
for i = 0 to 5 do {
  circle rad 0.12 fill i/6 at (i * 0.4, 0)
}
')

TeX math labels

With texlabels = TRUE (or texlabels = 1 in the source), a label written entirely as $…$ is typeset as TeX math, natively — KaTeX-grade quality with exact metrics, so boxes fit around formulas correctly. Write TeX commands with a single backslash in the pic source (escaped as \\ inside an R string):

rpic_svg('
box "$\\frac{1}{2\\pi}\\int_{-\\infty}^{\\infty} f(t)\\,e^{-i\\omega t}\\,dt$" fit
', texlabels = TRUE)

rpic extensions

Beyond classic pic, opt-in extensions cover linear gradient fills, hatch patterns, curly brace annotations, margin, fit, opacity, layers (behind) and more — each documented with live examples at rpic.dev. They are inert for classic input:

rpic_svg('
B: box wid 0.9 ht 0.55 gradient "steelblue" "white"
"gradient" at B.c
C: circle rad 0.3 hatch hatchangle 45 at B.e + (1.0, 0)
"hatch" at C.s below
brace from B.nw + (0, 0.15) to C.ne + (0, 0.15) up "extensions"
')

Errors you can point at

Compile failures raise a classed rpic_error condition whose info field carries the structured diagnostic — position (always relative to your source), kind, and a did-you-mean hint:

tryCatch(
  rpic_svg("bxo", circuits = TRUE),
  rpic_error = function(e) list(line = e$info$line, hint = e$info$hint)
)
#> $line
#> [1] 1
#> $hint
#> [1] "did you mean `box`?"

Where next

• vignette("circuits") — the native circuit-element library;
• vignette("class-and-animate") — CSS class hooks and the animation manifest;
• rpic_register_knitr() — write pic directly in R Markdown / Quarto chunks;
• rpic.dev — the full language documentation.

rpic documentation built on July 15, 2026, 9:06 a.m.